Seismic and post-seismic stability of tailings impoundments, considering the effect of reinforcement inclusions

ABSTRACT: Post seismic impoundment failures can be caused by the redistribution of excess interstitial pore water pressures generated during the seismic event or by the driving stresses that may exceed the available shear strength. This paper presents numerical analyses to evaluate the seismic and post seismic stability of a tailing impoundment, with and without waste rock inclusions. The tailings are modelled in the shaking phase using the PM4Sand constitutive model. The results show that the unreinforced impoundments (without inclusion) are subjected to medium to high displacements at the end of the shaking, and present two types of behaviour in the post-seismic phase: i) cases with controlled deformations for stable impoundment and ii) cases with increasing displacements leading to impoundment instability. Impoundments reinforced by waste rock inclusions show limited displacements under post seismic condition even when high pore water pressures developed during shaking.